Priority to German Patent Application No. 101 57 060.0, filed Nov. 21, 2001 and hereby incorporated by reference herein, is respectfully requested.
The present invention is directed to a printing press for multi-color printing, having a central plate cylinder.
From German Patent Application No. 197 23 147, a method and a device are known for driving a printing press having at least one integrated imaging device. To attain a high imaging speed, the drive of the printing form cylinder is released from the drive gear train; the printing form cylinder is driven by its own drive in the imaging operation at imaging speed; and, in a service position phase, the drive of the printing form cylinder is integrated in the drive gear train. In this context, each offset cylinder can be equipped on the peripheral side with two active areas, and two inking units and one imaging device can be assigned to each printing form cylinder. The offset cylinders are mounted on the peripheral side around the single impression cylinder.
The printing press described in German Patent Application No. 197 23 147 is further refined in the German Patent Application No. 100 35 354. In this printing press, a multiplicity of inking rollers of a dedicated ink-application unit is able to be brought into contact with a predefined plate section on a plate cylinder, and, additionally, the inking rollers are able to disengaged from a remaining plate section on the plate cylinder.
Also known from German Patent Application No. 100 40 980 is a transport device which has retention and guiding means for holding and guiding the sheets at the outer edges in a defined position, as well as for keeping them taut toward the outer sides. The forces required in this instance can be generated, at least in part, electrostatically.
Also generally known is the satellite printing principle that provides for the print units to be assigned in a satellite configuration to a shared impression cylinder (H. Kipphahn:xe2x80x9cHandbook of Print Mediaxe2x80x9d, Section 2.1.3.3 pp. 281-82; Springer Publishers, 2000).
The known printing presses require many expensive cylinders, so that their manufacture entails substantial outlay.
The DocuColor 40 printing system from Xerox is also known. It features a gripper-free conveyance of the printing sheets via electrostatic forces and a conveyor belt.
An object of the present invention is to provide a novel, inexpensive and compact printing press.
The present invention provides a printing press for multi-color printing, having a central plate cylinder (1), having at least two printing plates (5) mounted on the peripheral side, around which are arranged in a satellite configuration at least two blanket cylinders (3) having assigned inking units (7), including a transport device (13), which loops around the blanket cylinder (3) on the outside, in the manner of a closed, continuous belt, having printing sheets, which are pressed for the printing operation by compensating rollers (15) against the blanket cylinders (3), and having a control unit (11), which engages the particular inking unit (7) and the blanket cylinder (3) on the corresponding printing plate (5) and lifts it off of the other printing plate(s) (5).
Costs are able to be saved, in particular, because of the ability to economize on laser modules and impression cylinders. An inexpensive, uncomplicated, and compact printing press having only one plate cylinder is realized in a satellite type of construction.
One preferred specific embodiment provides that, for four-color printing, the printing press have four printing plates on the peripheral side, as well as, correspondingly, four blanket cylinders. In this context, one blanket cylinder is provided for each color, making possible a simple, reliable, and compact printing press design.
Due to cost considerations, the number of imaging units assigned to the single plate cylinder having up to four printing plates may be limited to one.
At least one of the compensating rollers may be configured between the plate cylinder and the transport unit, to render possible a most compact possible type of construction of the printing press.
The transport device advantageously has a conveyor belt which is electrostatically chargeable for purposes of conveying the sheets. This unifies the paper guidance and counter-pressure cylinders, due to the use in the statically chargeable belt. An exceptionally compact type of construction is able to be achieved as a result of the paper guidance provided by the conveyor belt and the integration of the counter-pressure cylinders in the same belt.
As described in German Patent Application No. 100 40 980, the transport device may optionally have retention and guide means to hold and guide the sheet in defined positions, in the area of its outer edges running in parallel to the conveyance direction; and means may be additionally provided for keeping the sheets taut toward the outer sides. This enables the individual sheets of a substrate to be printed on without the need for a flat supporting surface, such as a continuous belt. In the context of a one-sided processing, damage to the other side of the sheet caused by the action of resting on a belt is avoided, in particular. The forces necessary for retention and guidance may be implemented mechanically, magnetically and/or electrostatically, as discussed in the German DE 100 40 980.